This project focuses on the mechanisms by which cadherins, integrins and the cytoskeleton cooperate to regulate proliferation in endothelial and smooth muscle (vascular) cells. Aberrant proliferation of vascular cells plays a major role in the pathophysiology of atherosclerosis and arteriosclerosis, and likely is triggered by inflammatory changes in the local tissue microstructure. Understanding the molecular basis for how cues within the tissue microenvironment are integrated within cells to regulate proliferation is hence a priority in the development of rational strategies to interrupt progression of vascular disease. It is proposed that Rhomediated tension generated in the actin cytoskeleton couples signals from cadherins and integrins in an integrated mechanochemical signaling system to regulate proliferation in both endothelial and smooth muscle cells. Preliminary results suggest that cadherin-mediated cell-cell contact causes cell spreading against extracellular matrix to decrease, and thereby, inhibits cell proliferation. Controlling for changes in cell spreading revealed a novel cadherin-dependent stimulatory signal for proliferation. Both the spreading and cadherin-mediated proliferative signals require Rho-mediated changes in cytoskeletal tension. Specific Aim 1 will be to investigate the cooperative role of vascular cadherins and integrin-mediated cell spreading in the positive and negative regulation of cell proliferation. The investigator has developed a micropatterning tool to independently manipulate cell-cell contact and cell-substrate adhesion for this study, and will combine this tool with molecular approaches to probe the specific role of VE-cadherin and N-cadherin in proliferative signaling. Specific Aim 2 will be to examine the role of RhoA and cytoskeletal tension in the regulation of proliferation by cadherins and cell spreading. A novel cellular tension microsensor will be combined with microinjection and transfection approaches to distinguish the importance of RhoA and cytoskeletal tension in proliferation. Specific Aim 3 will be to examine the role of focal adhesions and cadherin-based contacts in the transduction of cytoskeletal tension into proliferative signals. This project will lead to an integrated molecular understanding of how endothelial and smooth muscle cells coordinate signals from cadherins, integrins, and cytoskeletal tension into a proliferative response, and may suggest new therapeutic strategies to interrupt the progression of atherosclerosis and arteriosclerosis. [unreadable] [unreadable]